1. Technical Field
Example embodiments relate to a test system, and more particularly, to a test system that performs a package test.
2. Description of the Related Art
Increasing the operating speed of memories in many applications and manufacturing memory devices that operate faster is widely required. A package test is necessarily performed to evaluate the memory devices that operate faster. The manufacturers test simultaneously many memory devices in order to reduce the cost of the backend process. A test system transfers simultaneously a test pattern to many memory devices on a test board through a branch configuration.
When data is transferred to memory devices that operate slowly through the branch configuration, there are few problems. However, when data is transferred to memory devices that operate faster through the Brach configuration, capacitive values existing in the memory devices becomes larger to increase a time constant. In addition, waves are reflected in the branch due to impedance mismatching. Therefore, input signals, e.g., test patterns, are not properly transferred to the memory devices that operate faster and signal integrity is degraded. In addition, when a number of layers that are packaged increases causing a gap between the layers, matching impedance is more difficult.